It's oddly not. Only to be a user or addict with a firearm. IIRC if you just like the way weed looks in your hand that doesn't make you a user, and there's plenty of reasonable doubt you're guarding it for grandma or whoever.
Of course people are still being convicted of weed and firearm, but it gets recorded as gun law violation and nobody cares, cuz left hates guns and right hates weed, so they'll never repeal it.